package org.vesselonline.dao;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.SessionFactory;
import org.hibernate.StaleObjectStateException;

/**
 * Adapted from <a href="http://www.hibernate.org/43.html">hibernate.org - Open Session in View</a>
 */
public class HibernateSessionRequestFilter implements Filter {

//  private static Log log = LogFactory.getLog(HibernateSessionRequestFilter.class);
  private SessionFactory sf;

  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
                      throws IOException, ServletException {
    try {
//      log.debug("Starting a database transaction");
      sf.getCurrentSession().beginTransaction();

      // Call the next filter (continue request processing)
      chain.doFilter(request, response);

      // Commit and cleanup
//      log.debug("Committing the database transaction");
      sf.getCurrentSession().getTransaction().commit();

    } catch (StaleObjectStateException staleEx) {
//      log.error("This interceptor does not implement optimistic concurrency control!");
//      log.error("Your application will not work until you add compensation actions!");

      // Rollback, close everything, possibly compensate for any permanent changes
      // during the conversation, and finally restart business conversation.  Maybe
      // give the user of the application a chance to merge some of his work with
      // fresh data... what you do here depends on your applications design.
      throw staleEx;
    } catch (Throwable ex) {
      // Rollback only
      ex.printStackTrace();

      try {
        if (sf.getCurrentSession().getTransaction().isActive()) {
//          log.debug("Trying to rollback database transaction after exception");
          sf.getCurrentSession().getTransaction().rollback();
        }
      } catch (Throwable rbEx) {
//        log.error("Could not rollback transaction after exception!", rbEx);
      }

      // Let others handle it... maybe another interceptor for exceptions?
      throw new ServletException(ex);
    }
  }

  public void init(FilterConfig filterConfig) throws ServletException {
//    log.debug("Initializing filter...");
//    log.debug("Obtaining SessionFactory from static HibernateUtil singleton");
    sf = HibernateUtil.getSessionFactory();
  }

  public void destroy() {}

}
